Add optional build of Hershey fonts to our build system.  See README file for details.
Add optional build of Hershey fonts to our build system.  See README file
for details.

svn path=/trunk/; revision=9368

FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot